Field of the Invention
The present invention relates to a gas extinguishing system for a predefined protected area, particularly in the form of a gridded structural system such as for example a small-parts storage system.
Background Information
It is known that reducing the oxygen concentration in enclosed rooms, which are for example only entered occasionally by humans and in which the furnishings therein react sensitively to the effects of water, to a value of e.g. approximately 12% by volume can counter the risk of fire in the respective spaces. At such oxygen concentrations, most combustible materials can no longer ignite. The main areas of application are IT areas, electrical switching and distribution rooms, enclosed facilities as well as storage areas containing high-value commercial goods.
An inert gas fire extinguisher is thus known for example from EP 2 186 546 A1 which is designed to render an enclosed protected area inert according to different sequences of events.
A further gas extinguishing system is known from DE 198 11 851 C1. This gas extinguishing system is designed to lower the oxygen content in an enclosed room to a predefinable base inerting level and in the event of a fire or when otherwise needed, to rapidly lower the oxygen content further to a certain full inerting level. To this end, the known gas extinguishing system comprises an inert gas source able to be controlled by a control device as well as a system of supply tubes connected to the inert gas source and the protected area through which the inert gas provided by the inert gas source can be fed into the protected area. Either a battery of pressure cylinders in which the inert gas is stored in compressed form, a system for producing inert gas (also informally called a “nitrogen generator”) or a combination of both solutions is conceivable as the inert gas source.
The preventative and/or extinguishing effect resulting from rendering a protected area inert is based on the principle of oxygen displacement. As is known, normal ambient air consists of approximately 21% oxygen by volume, approximately 78% nitrogen by volume and approximately 1% by volume of other gases. To effectively lower the risk of a fire starting in a predefined protected area, e.g. in an enclosed room, the oxygen content in the respective space is decreased by introducing an inert gas or an inert gas mixture such as, for example, nitrogen. With respect to extinguishing fire in the case of most solid matter, a preventative effect is for example known to begin once the percentage of oxygen drops below 15% by volume. Depending upon the flammable substances within the protected area, it may be necessary to further lower the percentage of oxygen to, for example, 12% by volume.
It is frequently the case that known prior art gas extinguishing systems designed to extinguish fire in enclosed rooms are not necessarily suited to lowering the risk or extinguishing fires in gridded storage or shelving systems such as for example small-parts storage systems since such storage/shelving systems frequently comprise a plurality of partitions in the form of individual compartments such that it is thereby in particular no longer a case of a single enclosed room. The design of vertical, high-density storage facilities in particular poses great challenges to conventional gas extinguishing systems. Upon a fire, the often very densely packed warehouse racks coupled with the associated high density of material impedes the effective, and above all prompt, extinguishing of the source of the fire.
Particularly in the case of small-parts storage systems such as tray shuttles or revolving shelving systems (paternoster systems), it is frequently necessary when a fire extinguisher system is used to control fire for the protected area to be “gently” flooded with extinguishing or inerting gas so that the extinguishing and/or fire-fighting action will not cause any damage to the storage system nor have any adverse pressure-related effect on the stored material.
Setting forth from a conventional fire extinguishing system designed and configured for enclosed and comparatively gas-tight rooms as described for example in EP 2 186 546 A1 or DE 198 11 851 C1, the present invention is based on the task of further developing same to the effect of being applicable to shelving and storage systems, particularly storage facilities having minimal stock separation in the form of for example vertical shuttle and paternoster systems.
Conventional fire extinguishing systems designed and configured for enclosed and comparatively gas-tight rooms are not readily applicable to such shelving and storage systems because such shelving and storage systems constitute a protected area without an actual gas-tight spatial shell. Whereas a defined protected area in a typical shelving and storage system frequently has an n50 value of 25/h to 50/h, the air exchange rate is significantly lower in enclosed rooms (for instance, a typical n50 value of a cold storage facility is e.g. 0.015/h to 0.03/h), as is recognized in EP 2 186 546 A1 or DE 198 11 851 C1.
Hence, conventional fire extinguishing systems for shelving and storage systems designed and configured for enclosed and comparatively gas-tight rooms are not suitable since, despite the limited quantity of extinguishing agent, it is not possible for such conventional fire extinguishing systems to build up the concentration of extinguishing gas any faster in the predefined protected area nor maintain the concentration of extinguishing gas.